Blower system for jet piercers



Sept. 2, 1969 A. M. MOYER ETAL 3,464,506

BLOWER SYSTEM FOR JET PIERGERS Filed June 27, 1968 2 Sheets-Sheet 1 Fi e. I8

INVENTORS. ALLAN M MOYER WILLIAM H. MC OARTHY W/LFRED M PETRELL .B Y @m EZJOM A f TO FPNEYS Sept. 2, 1969 A. M. MOYER ETA!- 3,464,506

BLOWER SYSTEM FOR JET PIEHCERS Filed June 27, 1968 2 Sheets-Sheet 2 INVENTORS.

ALLAN M. MOYER WILLIAM R. MC CART'HY W/Lf RED M. PETRELL AT T OPNEYS United States Patent O 3,464,506 BLOWER SYSTEM FOR JET PERCERS Allan M. Moyer and William R. McCarthy, Babbitt, and

Wilfred M. Petrell, Embarrass, Minn., assignors to Reserve Mining Company, Silver Bay, Minn., a corporation of Minnesota Filed June 27, 1968, Ser. No. 740,684 Int. Cl. E21c 21/00 US. Cl. 175-14 8 Claims ABSTRACT OF THE DISCLOSURE A jet piercing machine having a vertically suspended, rotating blowpipe assembly that produces a high velocity, high temperature flame for forming blast holes in an ore formation. Water is provided to cool the burner head and to form steam that aids in ejecting the disintegrated ore and other debris from the blast hole. A fan unit is mounted in an air duct system on the machine so as to discharge a high velocity curtain of air over the blast hole in a direction away from the machine to carry the steam, combustion products, disintegrated ore and other debris emerging from the blast hole away from the machine to minimize damage to the machine.

BACKGROUND OF THE INVENTION Field of the inventin.-This invention relates generally to the field of jet piercing machines capable of forming blast holes in rock or ore formations by spalling or melting the rock or ore, and more particularly relates to apparatus for producing a high velocity curtain of air over the blast hole to deflect materials being ejected from the blast hole away from the machine to prevent damage thereto.

Description of the prior art.For the past several years, jet piercing machines have been used in taconite mines for making vertical blast holes in the taconite formations. After these vertical blast holes are formed in the formation in a predetermined pattern, explosives are placed in the holes and detonated to break up the taconite so that it can be removed from the mine. Instead of chopping or abrading holes in the taconite, as is normally done with ordinary types of drills, a jet piercer directs a high-velocity, high-temperature flame against the taconite causing disintegration by a spalling or melting action.

The jet piercing machine utilizes a rotating blowpipe having a burner at the lower end to direct all the flame against the rocks as the blowpipe is lowered into the rock formation to form the hole. The flame from the burner is produced by burning a petroleum base fuel such as kerosene with oxygen. Water is also provided to the burner and is discharged from the burner into the blast hole adjacent the burner head. As the water passes through the burner, it provides a cooling action, and when it is discharged from the burner, it turns to steam as it comes in contact with the extremely hot products of combustion. The water, in changing to steam, increases tremendously in volume. This increase in volume causes an increase in pressure within the blast hole to force the steam and combustion products upwardly out of the blast hole. The velocity of the steam and combustion products escaping from the hole around the blowpipe is sufiiciently high to carry the spalled taconite and other debris out of the hole.

This combination of materials is thus ejected upwardly 3,464,506 Patented Sept. 2, 1969 "ice out of the blast hole around the blowpipe assembly at a relatively high velocity. In the past, this material has caused many problems. The spalled taconite being ejected from the hole ranges in size from very fine sand-like particles to pieces as large as one inch in diameter. The jet piercing machine itself is positioned directly adjacent the blast hole so that these taconite particles cause damage to various portions of the machine. For example, the area directly above the hole being pierced contains a bushing mechanism and drill stem which are subject to extreme wear if these materials constantly impinge upon it. The steam itself causes damage to the machine since it tends to condense on the machine causing rusting to occur and also causing dirt to adhere to the machine. Basically, this combination of materials including steam, water, combustion products, taconite particles and other debris will eventually cause considerable damage to the jet piercing machine if not somehow prevented from impinging upon it.

An attempt to overcome these problems was made in the prior art by providing an exhaust system on the jet piercer machine. These prior art systems draw the steam and other materials from near the drill hole into a blower. The material, after passing through the blower, is forced through ducts to the rear or side of the machine and is discharged into the atmosphere.

With these prior art systems, the vacuum developed near the blast hOle by the blower was sufficiently strong to collect only about seventy-five percent of the material being ejected from the hole. The remaining material not picked up by the blower system tended to cause the previously mentioned problems. For example, the remaining steam goes upwardly along the front of the machine causing ice build-up on the mast rails, which reduce the penetration rate and decreased production. Further, the steam when mixed with the products of incomplete combustion, formed acids which caused destruction of metal areas of the machine. In actual practice, some panels on the front of the machine had to be replaced as the result of this corrosive action. Further, the same type of corrosive action took place in the duct work causing damage to it. In general, the entire machine was subject to corrosion and sediment build-up.

Another disconcerting problem with prior art systems Was that the taconite particles passing through the duct work and blower caused extensive damage to them. Again, in actual practice, the very abrasive taconite particles caused damage such that repairs to the blower were required about every three months.

SUMMARY OF THE INVENTION The present invention has eliminated the problems that arose in utilizing the prior art blower systems. In the present invention, fresh air is drawn into the blower system near the top of the machine, where the air is relatively clear, and discharged at a high velocity just over the top of the drill hole. This high velocity air stream blows away virtually all of the steam and combustion products being ejected from the drill hole and also blows away the greater majority of the taconite particles and other debris being ejected from the drill hole. All of these materials are blown away from the machine before they come in cont-act with any part of the machine. The wear rate on the duct work and blower is negligible since no taconite particles are carried through them. Since the steam and combustion products are blown quickly away from the machine, corrosion and icing of the machine is also eliminated. The machine remains much cleaner so that it is easier to detect worn or broken parts and to repair them. Further, the above-described corrosion problem is virtually eliminated. The new system reduces operating costs, increases production and reduces maintenance costs.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE I is a view in front elevation of a jet piercing machine, portions thereof being broken away, incorporating our invention;

FIGURE 2 is a view in side elevation, portions thereof being broken away, of a jet piercing machine incorporating our invention;

FIGURE 3 is an enlarged view in vertical section, taken along line 33 of FIGURE 1, showing our invention in an operative condition, portions thereof being broken away and portions being shown in section;

FIGURE 4 is a horizontal section taken along line 44 of FIGURE 3;

FIGURE 5 is a horizontal section taken along line 5-5 of FIGURE 3; and

FIGURE 6 is an exploded perspective view of a portion of the duct work of our invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, wherein like numerals will be used throughout the several views to identify like elements of the invention, there is disclosed a jet piercing machine 10 of the type used by the assignee of the present invention in its taconite mining operations. Machine 10 is a self-propelled unit having caterpillar type treads 11 and 12, each of which is driven by an electric motor located in the cab. Machine 10 is thus capable of independent movement over the surface of the usual openpit mine.

Once the machine 10 is situated at the proper position in the mine, three hydraulic jacks 13, 14 and 15 are activated from a control panel within the cab to level the machine so that a vertical hole will be formed. All of the basic operating controls for machine 10 are mounted on a control panel located within the sealed cab, entrance to which is provided by a door 16 in the side of the cab. Also located within the insulated cab is a water tank. Fuel tanks are mounted in the deck of the machine and oxygen connections are located at the rear of the machine.

Mounted on the top of machine 10 is a blowpipe supporting mast 18, the top portion of which has been broken away and not shown. Supporting mast 18 carries a blowpipe assembly 19 in a vertically suspended position. The mechanism at the top of mast 18 which is not shown,

includes a rotary drive mechanism for rotating blowpipe assembly 19, a rotary joint to permit rotation of assembly 19 without disrupting flow of fuel, oxygen and water thereto, and a hoisting mechanism for raising and lowering blowpipe assembly 19. Since these structures are standard components of a jet piercing machine and since their operation is well known to those skilled in the art, they have not been shown or described in detail herein.

The vertically suspended, rotatable blowpipe assembly 19 comprises several different parts. First, there is a long tubular member 20 called the main drill pipe. A splined member called the shaft extension (not shown) is attached to the upper end of main drill pipe 20. Attached to the upper end of the shaft extension is a rotary joint (not shown). The previously mentioned rotary drive mechanism supported by mast 18 thus cooperates with the splined shaft extension to cause rotation of blowpipe assembly 19.

Attached to the bottom end of main drill pipe 20 is a burner assembly, generally designated by the numeral 21. Burner assembly 21 includes a kelly extension 2101 connected to the bottom of main drill pipe 20, and a reamer shell 21b attached to the bottom end of kelly extension 210. Reamer shell 21b has longitudinal teeth 210 formed around the outer periphery. Mounted within reamer shell 21b is the burner head itself.

As previously mentioned, fuel, oxygen and water are provided to the blowpipe assembly 19 through a rotary joint suspended near the top of mast 18. Fuel, oxygen and water lines extend downwardly from the rotary joint through main drill pipe 20 to the burner head. When the fuel and oxygen are turned on and ignited, the burner head produces a high velocity, high temperature flame that is emitted through a number of ports in the tip section of the burner. This flame melts or spells the taconite as blowpipe assembly 19 is lowered into the taconite formation. Blowpipe assembly 19 is also rotated as it is being lowered so that a hole is formed having a diameter slightly greater than the diameter of the blowpipe assembly 19. Reamer shell 21]; protects the burner and also breaks up fused rock around the surface of the hole so that it can be blown out of the hole. The hardened teeth 21c assure that a hole of proper diameter will be formed.

At the same time that the fuel and oxygen are ignited, the burner head is provided with a flow of water which acts to cool the burner head. This cooling water is emitted through a plurality of drilled holes into the area surrounding the burner head. The water being emitted into the hole around the burner head assists in breaking up the rock and in ejecting the rock particles from the hole. The water immediately turns to steam upon being ejected into the hole and thus increases tremendously in volume to increase the ambient pressure within the hole. The steam, in rushing to escape upwardly through the hole, carries with it the rock or taconite particles that have been broken loose by the flame. These particles are ejected upwardly from the hole at a relatively high velocity so that the hole is constantly being cleared of spalled particles and other debris. Continuous drilling is thus possible with this machine.

Mounted on the front end of machine 10 is a guide bushing support structure 25 that extends outwardly and generally horizontally therefrom over the area in which the hole is to be drilled. Formed in guide bushing support structure 25 is a vertical hole or opening 26 through which blowpipe assembly 19 extends. Vertical opening 26 is provided at its upper end with a properly configured seat 27 for a guide bushing 28 seated therein. Guide bushing 28 is provided with an axial opening carrying a hearing insert 29 through which main drill stem 20 extends. Guide bushing 28 thus acts as a bearing for the rotating blowpipe assembly 19 and prevents lateral movements thereof once machine 10 has been placed in position at the selected site.

A blower assembly generally designated by the numeral 30 is provided to carry the steam, combustion products, disintegrated ore particles and other debris away from machine 10 to minimize damage thereto. Blower assembly 30 includes an air intake duct portion 31 that extends upwardly through the roof of machine 10 into an area of relatively clean air. Blower assembly 30 also includes an air discharge duct 32 mounted on the machine 10 having an air discharge opening 33 located just below guide bushing support structure 25. Air discharge opening 33 is thus located above the level of the blast hole opening and generally between the blast hole opening and the body of the machine itself. Discharge opening 33 has a generally rectangular configuration, in the preferred embodiment, with a relatively narrow vertical dimension and a wide horizontal dimension.

A vertically extending intermediate duct section 34 extends through the machine 10 to connect air intake duct 31 with air discharge duct 32. An electrically driven fan unit 35 is mounted within duct 34. Fan unit 35 is designed to draw a large volume of air from air intake duct 31, and the air intake opening 31b therein, and discharge the air through opening 33 in discharge duct 32.

When fan unit 35 is energized, a large volume of air is discharged through opening 33 to form a curtain of air moving at a high velocity over the blast hole, as best shown in FIG. 3. Since the vertical dimension of discharge opening 33 is quite small, the curtain of air flowing outwardly therefrom is also relatively thin, thus assuring high velocity.

The materials being ejected from the hole tend to expand outwardly as they are thrown upwardly therefrom so that they would normally strike the entire under surface of support structure 25. Therefore, the discharge opening 33 is of sufiicient width to provide a moving curtain of air beneath the entire under surface of support structure 25. All of the steam, combustion products, disintegrated ore particles and other debris being ejected from the hole thus come in contact with the high velocity air curtain before they have an opportunity to strike any portion of the machine. The air curtain has suflicient velocity to deflect these materials away from the machine so that damage to the machine is minimized.

In order to further assist in deflecting these materials away from machine 10, a plurality of skirt members 37, 38 and 39 are attached to the machine so as to provide a chamber about the blast hole opening. Skirt members 37 and 38 are attached to opposite sides of support structure 25 and extend downwardly therefrom to a position closely adjacent the earths surface. Skirt member 39 is secured to the bottom surface of discharge duct 32 and also extends downwardly therefrom to a position closely adjacent the earths surface. The chamber thus formed by the skirt members thus is completely open opposite discharge opening 33 to permit the passage therethrough of the materials being deflected by the curtain of air.

The present invention thus provides a means of continuously carrying away from the jet piercing machine the materials emanating from the blast hole, including steam, combustion products, disintegrated ore particles and other debris. With this system, the rock or taconite particles cannot harm the duct Work or fan unit since only clean air is drawn therethrough. Further, the abrasive particles do not have an opportunity to pass upwardly into the guide bushing structure to cause damage to the bearing structure therein. The steam and combustion products do not impinge upon the machine itself so that icing and corrosion effects are eliminated. The present invention has been successively tested by the assignee of this application and has been found to considerably reduce operating and maintenance costs and to increase production accordingly. While we have described the present invention as used in connection with jet piercing machines for taconite mining, it is evident that it has application wherever jet piercing machines are utilized. Therefore, we do not intend to be limited to the details of the disclosure but only by the scope of the appended claims.

What is claimed is:

1. In a jet piercing machine having a mast structure and hoisting mechanism designed to support a vertically suspended, rotatable blowpipe assembly and to lower said blowpipe assembly into an ore formation while rotating said blowpipe assembly to form a blast hole therein, said blowpipe assembly being provided with fuel and oxygen from said machine to produce a high-velocity, hightemperature flame to spall or melt said ore, and with a flow of water to cool the burner assembly thereof and form steam as the water comes in contact with the hot products of combustion, said steam and combustion products in their exit from the blast hole around the blowpipe assembly attaining suflicient velocity to carry the disintegrated particles of ore out of said blast hole; the improvement comprising means for carrying the steam, combustion products, disintegrated ore particles and other debris away from the machine to minimize damage to the machine therefrom, said means comprising:

(a) an air intake duct mounted on said machine having an air intake opening located away from the blast hole in an area of relatively clean air;

(b) a fan unit mounted on said machine designed to move a high volume of air when operated;

(c) an air discharge duct mounted on said machine having an air discharge opening located above the level of said blast hole opening and between said blast hole opening and said machine; and

(d) means including an intermediate air duct having said fan unit mounted therein connecting said air intake duct and said air discharge duct, said fan unit drawing air from said intake opening and forcing said air out through said discharge opening to form a curtain of air moving at high velocity over said blast hole to carry the material being ejected from said blast hole away from said machine to minimize damage thereto.

2. The apparatus of claim 1 wherein said air discharge duct has a generally rectangular discharge opening with a relatively narrow vertical dimension and a wide horizontal dimension to provide a relatively wide, high velocity curtain of air over said blast hole.

3. The apparatus of claim 1 wherein a guide bushing support structure is mounted on one side of said machine and extends outwardly and generally horizontally therefrom over the blast hole area, said support structure having a vertical opening therein through which said blowpipe assembly extends, said vertical opening having a guide bushing seated therein surrounding said blowpipe assembly acting as a bearing therefor and acting to prevent lateral movements thereof, and wherein said air discharge opening is a horizontally extending, generally rectangular opening positioned directly beneath said support structure so that said curtain of air carries away the major portion of said steam, combustion particles, disinte grated ore particles, and other debris before they strike said guide bushing support structure and other portions of said machine.

4. In a jet piercing machine wherein a vertical blast hole is formed in an ore formation by lowering into the formation a rotating blowpipe assembly that produces a flame to spall or melt the ore, said blowpipe assembly being provided with a flow of water for cooling and for forming steam to assist in ejecting debris from the blast hole, the improvement comprising means on said machine for providing a high velocity curtain of air from the direction of the machine over said blast hole to carry said steam, combustion products, and debris away from said machine to minimize damage thereto.

5. The apparatus of claim 4 wherein said means for providing a high velocity curtain of air includes air duct means mounted on said machine having:

(a) an air intake opening located away from said blast hole area in an area of relatively clean air;

(b) an air discharge opening located above said blast hole area and between said blast hole and said machine; and

(c) fan unit means mounted therein to provide said air flow.

6. The apparatus of claim 5 wherein said air discharge opening has a generally rectangular configuration with a relatively narrow vertical dimension and a wide horizontal dimension to provide a relatively wide, high velocity curtain of air over said blast hole.

7. The apparatus of claim 6 wherein a guide bushing support structure extends outwardly from said machine over said blast hole area, said support structure having a guide bushing mounted therein through which said blowpipe assembly extends, and wherein said discharge opening is positioned beneath said support structure so that said curtain of air carries away the major portion of said steam, combustion products and debris before they strike said guide bushing support structure and other portions of said machine.

8. The apparatus of claim 7 wherein skirt members are attached to said support structure on opposite sides thereto and beneath said discharge opening, and extend to a position closely adjacent the earths surface, said skirt members thereby providing a chamber about said blast hole opening, with the side of said chamber opposite said discharge opening being completely open to permit the passage therethrough of said materials being deflected by said curtain of air.

References Cited UNITED STATES PATENTS 7/1955 Redman 175212 X 1/1956 Lenhalt 175212 X 2/1957 Robbins 175-209 X 3/1957 Carle 175212 X 4/1967 Ross 175-11 10 NILE C. BYERS, 1a., Primary Examiner US. Cl. X.R. 

